This study will examine and compare the effects of intense exercise on the release of catecholamines in patients with congenital adrenal hyperplasia (CAH) and in healthy persons. Catecholamines are hormones (adrenaline and noradrenaline) that are produced by the adrenal glands and released into the blood stream during stress, such as trauma, illness, intense exercise, or low blood sugar. The study will also assess exercise tolerance in patients with CAH, compared with healthy persons.